It is becoming increasingly common to use so-called alternative fuels, such as propane or natural gas, in internal combustion engines or hydrogen in fuel cells. Often such engines are converted to use one or two or more sources of fuel, such as gasoline and natural gas. The operator has the ability to switch between sources depending on the availability and price of these fuels.
Many vehicles are manufactured to operate on gasoline only and are converted to run on two or more fuels. The vehicles are manufactured with storage tanks for gasoline, pumps for moving the gasoline from the tank to the engine, and carburetors or fuel injectors for introducing the fuel and the required amount of air for combustion into the engine.
Gaseous fuels such as propane, natural gas, and hydrogen must be stored in pressurized cylinders to compress the gas into a manageable volume. Increasing the pressure to the highest level that can safely be handled by the pressurized storage cylinder increases the amount of fuel that can be stored in that cylinder and extends the distance that the vehicle can be driven to its maximum. Typical storage cylinder pressures range from 2,000 to 5,000 psig.
Internal combustion engines cannot operate at such a high pressure, and the pressure of the gas must be reduced to a level at which the engine can be operated safely. Typically the pressure must be reduced to approximately 20 to 200 psig for use in internal combustion engines.
The pressure must also be regulated as it is reduced to ensure that the pressure of the fuel entering the engine is nearly constant even as the pressure in the storage cylinder is reduced. At the same time, the pressure regulation must permit as much gas as possible to be removed from the storage cylinder, and thus permit the pressure in the storage cylinder to fall to as close to the operating pressure as possible. A high pressure difference across the pressure regulator means that unused fuel remains in the storage cylinder and is unavailable to the engine.
Conventional pressure regulators having one or more stages over which the pressure is reduced are well-known and have long been used to reduce the pressure and regulate the flow of compressed gases. Conventional regulators typically use various arrangements of springs, diaphragms and machined parts to reduce pressures exerted by gases flowing through the regulators. One major concern is the risk of failure of a regulator, as failure can lead to a potentially dangerous release of the compressed gases into the atmosphere.
Another concern is the vulnerability of flow components (including pressure regulators) carrying alternate fuels to crash damage. It is desirable to take steps to protect such components to minimize the risk of failure thereof in an unsafe or catastrophic manner if the vehicle is involved in an accident. To this end, internally-mounted pressure regulators are known which are adapted for mounting on a pressure vessel with a portion thereof positioned inside the pressure vessel.
However, conventional internally-mounted regulator devices do not also include a number of features and/or components which are desirable, such as a manual shut-off valve and an in-tank solenoid valve assembly. Such features are not included in conventional internally-mounted regulator devices because the size of the opening in the pressure vessel wall so limits the size of the conventional internally-mounted regulator device that including these features has not been feasible for various reasons. For example, the size of the opening is limited because a relatively larger opening would tend to reduce the strength of the pressure vessel.
There is therefore a need for a gas flow regulation module which overcomes at least one of the deficiencies of conventional internally-mounted pressure regulator devices.